To advance the performance of a semiconductor integrated circuit, the performance of a field effect transistor serving as a constituent device must be advanced. For advancing the device performance, scaling down of the device is effective. For this reason, device performance has been improved by scaling down the device by micro patterning. However, as micro patterning advanced, a technical barrier to be solved becomes high at the same time. According to the international semiconductor roadmap, especially in relation to a technique for forming source and drain portions, a solution for realizing a junction having a depth of 10 to 20 nm in a drain-extension portion in the 65-nm generation or later cannot be found in the existing circumstances.
In this background, in order to improve both suppression of short channel effect and reduction of junction leakage, a device using Schottky source and drain to which an impurity segregation technique is applied is proposed (JP-A 2005-101588 (KOKAI)). In particular, in the 45-nm generation or later, a channel resistance caused by scattering of carriers is not a prevailing factor that degrades a drain current because of a small gate length. For this reason, improvement of device performance relying only to micro patterning is very difficult. Therefore, in order to realize further improvement of performance, a device using a Schottky source-drain maximally utilizing the characteristic feature of a Schottky junction which can inject high-speed carriers into a channel is desired (K. Ucida et al., Appl. Phys. Lett., 76, 3992 (2000)). However, a device structure using a conventional Schottky source-drain has the following problem. That is, the merit of the Schottky source-drain which can inject high-speed carriers into a channel is not always maximally utilized.
Thus, the device using a conventional Schottky source-drain has a merit for short channel effect and suppression of junction leakage. However, the merit of the Schottky source-drain which can inject high-speed carriers into a channel is not always maximally utilized. More specifically, in order to improve the device performance by using an increase in rate of injection by the Schottky source-drain, a device structure must be optimized. However, up to now, it cannot be said that the device structure is optimized.